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  1. #1

    Default Wings and downforce

    Watched an episode of Wheeler Dealer featuring a 1995 Ford Escort Cosworth RS 2.0L turbo AWD.

    The car came with a double rear wing from the factory. They had the original designer on the show who showed his original three wing design which basically centered a wing between the ones the bean counters allowed.

    They put the car in a wind tunnel with two then added the originally designed third wing. The 3rd wing added over 25 lbs of additional downforce at 100 mph of wind. 35% more downforce.

    More interestingly the net result added more downforce in front too due to the way the car distributed weight as it settled.

    Theres little doubt what the SVO's 2nd wing likely did to its downforce. Does anyone have any stats or data?

    What about the Saleen wings? Has anyone ever stackedan SVO wing on top of a Saleen base?

    I remember back in the 90's AutoKraft cut up an 86 GT / 87-93 LX style wing and grafted it together with an 87-93GT base. Relatively cheap way to build a giant Saleen - ish - style wing.... Similar mayhem could be done to make a second wing above the Saleen base.

    Anyway - fun stuff.
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  2. #2
    FEP Super Member xctasy's Avatar
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    SVO rear wing down force, 50 pounds at 100 mph, with an additional reduction in drag of 0.02 by reduced wake propogation .

    On the 1985 European Ford Sierra RS Cosworth, a front air dam which gives “negative lift", and a large rear wing which generates up to 45 lbs downforce. 8th paragraph, http://www.motorsportmagazine.com/ar...6/46/road-test

    (0.34--->0.32 on the XR4i Sierra, and 0.38-->0.36 on the first year SVO.

    A lot less than the A1 open wheeler G-stream wing, which all the AI and World Challenge guys are using; that makes 600 lbs of downforce at 100 mph.





    The first years Merkur XR4TI used a highly modified version of the 1982 Sierra XR4i 2.8 V6 rear"spolier"




    This one here. It then got toned down to a single bustle back areo deck





    The SVO one itself, was essentially the Sierra XR4i 2.8 which was almost exactly from the 1981 one year before the Euro Ford Sierra, the Ford Probe III



    http://www.svoca.com/forum/showthrea...Wings-Function
    Quote Originally Posted by Billibew
    According to the book Mustang Forty Years by Randy Leffingwell. "A feature exclusive to the Mustang SVO was the bi-level rear wing assembly, which was effective in generating -0.011 lift versus +0.085 for a base Mustang. The top wing was designed to spill the airflow rearward, so that the air would tumble onto the rear lip of the lower wing and push the vehicle down, improve gas mileage." Page 294 side note of associated picture on that page.

    Further interest on page 301. "Then there was the controversial bi-plane rear wing. A drag racer from the 1960's named Al Turner was involved in the grass-roots racing promotions that SVO was doing as part of Ford Motor Sports efforts. Turner had spent time in Europe and Australia for Ford, and he was familiar with Ford of Europe's Sierra XR-4i sports coupe series that wore a distinctive two-level rear spoiler. He recommendeded it and pushed hard for its adoption to the Mustang. Older staffers within SVO who had witnessed the distinctive grille of the Edsel warned Turner that high-visiblility features could hurt a car as much as help. After toning down the spoiler design from the Sierra (on which the top wing was aligned level with the roof line), everyone finally agreed that it probably did fit the GT image, even though it never would be appropriate for the tire-squealers."

    I hope this helps. By the way this is a great book to have around for all Mustang enthusiasts.
    It wasn't just the 500 build homolgation variant of the Ford Sierra RS 500 Cosworth version of the orginal 5000 build Sierra Cosworth that had the most crazy spolier.



    The whole rear drive platform with four wheel drive was kept alive till 2003 with the Escort Cosworth RS 500, and its insane spolier






    For the SVO Mustang, the co-efficent of lift is measured at the front and the back wheel bearing plates or scales in a stationary, non rolling road wind tunnel at Lockheed, Georgia, after University of Maryland aerodynamics checks for concept on 1/4 scale models. That's where the early work was done by Ford USA, the European Sierras and Merkur XR4Ti's were done elseware, Ford had major issues getting the calibration of the drag factors correct when tested in other wind tunnels.

    The 50 pounds figure at 100 mph sounds about right. That level of reduction in lift is simply massive. Do do it while reducing the drag co-efficent 0.02 was the icing on the cake.

  3. #3
    FEP Super Member xctasy's Avatar
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    dtmilsaps pictures


  4. #4

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    Reduced drag AND more downforce is a winning combination.

    Thank goodness Ford got as much right with the foxbody cars in a wind tunnel as they did! heaven knows many of us were not lifting off the loud pedal let alone slowing down when the ol 5.0 was eating its steady diet of air/fuel and the selected gears ratio just kept building.

    Not sure how fast these cars would actually go from the factory - the speedometer only goes to 85 - but it's sufficient to say Motortrends's as tested 148.5 in 4th goes right out the window after the silencer is removed and the timing is advanced and somebody lets one keep eating in 4th or throws one in 5th. Then there's the easy bolton headers and throttlebodies and intakes and boost that drive up the score even higher. Good thing most of us also throw some rear gears in them to go after acceleration or at least have sense enough (usually) to stay out of them.

    Design principle used: "brakes are for quitters...."

  5. #5
    FEP Power Member Mikestang's Avatar
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    Curios about the downforce added with the svo upper, that thing can barely hold itself up let alone bear down force on the back of the car at high speed.

    Saleen wing downforce I would be interested to hear about. I have the Steeda Aero spoiler in the back of my blue car. At 130 mph it pushed the back of the car down about 1/2 in, measured at the rear shock.
    1986 Ford Mustang GT-

    Not much stock stuff left
    347 NA power, CNC ported heads, Extrude honed Trick Flow Intake, Custom Cam
    Suspension, custom k- member, TQ arm/pan hard rod... Much more
    Restored and ready to race, made to go fast while cornering

    1981 Mustang GT-

    Old SCCA A-Sedan National Champ car
    In the middle of rebuild

    1986 LX Sedan-

    Plans to be determined...

    "Every day I learn how much I don't know"

  6. #6
    FEP Super Member xctasy's Avatar
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    That's how you measure down force without four balance scales, or a rolling road with four balance sacales under the wheels in a windtunnel. Another is by laser through a tunnel.

    see "The secret racing test tunnel no one wants to talk about..."

    Lost in rural Pennsylvania, hidden from prying eyes, there is a tunnel....
    http://www.roadandtrack.com/motorspo...anassi-tunnel/


    and http://www.racecar-engineering.com/a...f-laurel-hill/


    https://www.youtube.com/watch?time_c...&v=s-f_0z3HARI


    The easiest is by four 68 dollar head lamp sensors, RX8, Lexus sedans and SUV's with HID lights always have them for dip for point control to stop dazzling other drivers), Mazdas have one, Lexus sedans, two, and 4wd SUV's, four. Don't buy the factory stock 400 dollar items. From this, you can determine ride height at speed, and then remove or add the aero device(s).

    These things read ohms resistance like an AFR meter, not voltage like and O2 sensor, so that quotient computes average ride height at speed.

    Sorry about the Metrics, fellas, 44 mph, 62 mph, 87 mph.....

    Ride height at 1850 ohms is 675mm or 26.6 inches static on a Lexus LS400, and there is an ohm reading static, and another dynamic, and the historgram on a Cat 5 Fluke meter is a great way of nailing it.







    http://www.autospeed.com/cms/article...pment&A=113225

    Quote Originally Posted by Julian Edgar
    The trend is downwards as speed rises - since (very roughly) about 4 ohms = 40 thou of ride height, you can see that the average ride height has dropped by 40 to 80 thou as the speed has gone from 44 - 87 mph. (That might seem a trivial amount but it is indicative of some downforce occurring at the front of the standard car at speed. Most cars develop lift.)
    If your spring rates are known in pounds per inch, then downforce is proportional to fractions of inches. The static ride height can be determined, and then the dynamic ride height at speed. Your GoPro can do that.

    Standard Heidts IRS camera shots with a graticle and measuring stick.

  7. #7
    FEP Power Member Mikestang's Avatar
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    I know my rear spring rates. But there is a factor there I don't know how to calculate. The ratio of pushing down on the chassis vs the angle of the arm and the spring setting on the arm. Since the spring is not on the axle it is not a direct force on the spring.

    They guy I bought my orange car helps me with this stuff. We put a ton of sensors on my car and logged all the susp heights yaw rates, brake temps, tire temps... It was an interesting day. But I am not a consistent enough driver to really take advantage of most of it.
    1986 Ford Mustang GT-

    Not much stock stuff left
    347 NA power, CNC ported heads, Extrude honed Trick Flow Intake, Custom Cam
    Suspension, custom k- member, TQ arm/pan hard rod... Much more
    Restored and ready to race, made to go fast while cornering

    1981 Mustang GT-

    Old SCCA A-Sedan National Champ car
    In the middle of rebuild

    1986 LX Sedan-

    Plans to be determined...

    "Every day I learn how much I don't know"

  8. #8

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    Exactly the type of discussion topics I was hoping my initial post would cause.

    Would love to see pictures and wiring diagrams of what others have built to measure this stuff.

  9. #9
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    To me, 50 pounds of downforce is not worth 100 pounds of ugly!
    1978 Fairmont 2 door sedan, 428CJ 4speed. 9.972ET@132.54mph. 1.29 60 foot
    Replaced the FE big block with my 331/4 speed in my Fairmont, best 10.24ET @128 MPH.
    1985 Mustang LX hatchback NHRA Stock Eliminator 302 4 speed best in legal trim 12.31@107 mph, but has gone 11.42@115 with aftermarket intake, carb, and iron Windsor Jr. heads.New for 2012! 331 cube SB Ford, AFR 185 heads, solid flat tappet cam, pump gas; 10.296ET@128.71 mph, 1.37 60 foot.
    1979 Zephyr Z7, all original 302 auto, 2nd owner.

  10. #10
    FEP Super Member xctasy's Avatar
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    I actually agree, 100%.

    Quote Originally Posted by mcfairmont View Post
    To me, 50 pounds of downforce is not worth 100 pounds of ugly!
    Australian Peter Brock had brainstorming sessions in his sand pit,




    creating RPO Holden Sedans that looked like they had slept with a German Polytechnic students acid fueled design session.



    Holden Motor Company was a devision of GM, and had to face Milbrooks Proving Ground Engineers form the USA when covering off wacko cars like the Holden Calais Director, with an Energy Poloriser, and 100 pounds of plastic"EccoModder" plastic.

    Understanding life from an Ecomodder persective as I do, the later GM certified respoenses for the SV Holden Commodore had very aero dynamic packages, which were only added after wind tunnel time. Peter Brock stole the march on Twin Throttle Body EFi and aero cladding. Y The car below was tested in the MIRA wind tunnel in the UK and made by Bolwell in Melbourne. Ugly is still U-G-L-Y, you ain't got no aliby....

    Its an American instituation to make wings, but to do so on a bluff four door sedan is crass and low rent. IMHO, The Superbirds did it with glass, so did the CSL 3.0 BMW.

    On the SVO, the issue was the soft material type. On the Saleens and other special Mustangs, it was great quality and on a proper low 2 or 3 door muscle car, I don't mid it so much.

    "When Plastic Pigs Fly - 1988-90 Perkins/TWR HSV Commodore SS Group A SV "

    https://www.carthrottle.com/post/ajg3r65/



    Truly the uglist piece of crud to share the Antipedean, South Pacfic or Australiasian road system ever.





    Of course, there are a percentage of people who forget about all about its "OBSCENE 'ugliness'" and ....


    only remember the NASCAR 355 conrods,
    Windsor style heads, and
    twin throttle body Rover Vittese 3500 style EFI unit and

    how awesome a factory based 5 liter iron OHV engine sounded making 480 hp net , running at 7000 to 7500 rpm for 620 miles and 6 hours, round and round and round, for 161 laps.





    The "Darth Vader" Walkinshaw Group A "SV" Commodore was another example of Cyborg Polyethalyne "cladding" added to reducing wake forming eddie areas in a bluff, 0.43 drag factor sedan body.

    VL Commodore = 0.43
    VL Group A Walkinshaw = 0.32

    Drag was reduced by 25% relative to its HDT VL Group A SS predecessor


  11. #11
    FEP Super Member xctasy's Avatar
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    Quote Originally Posted by Mikestang View Post
    I know my rear spring rates. But there is a factor there I don't know how to calculate. The ratio of pushing down on the chassis vs the angle of the arm and the spring setting on the arm. Since the spring is not on the axle it is not a direct force on the spring.

    They guy I bought my orange car helps me with this stuff. We put a ton of sensors on my car and logged all the susp heights yaw rates, brake temps, tire temps... It was an interesting day. But I am not a consistent enough driver to really take advantage of most of it.
    I do strain gauges for a living. The basic rule is how many gallons of water do you need to get one Ohm difference. Then measure the cement to wheel arch depth static. Normally about 632 mm or 24.875" on a stock ride heigh Stang. A gallon of water weighs

    At a very cold room temperature
    A pint's a pound, the world around.
    (Sixteen fluid ounces of water weighs ~16 ounces, avoirdupois weight.)
    A gallon is 4 quarts, or 8 pints, and thus weighs ~8 pounds
    A US liquid gallon of water weighs about 8.34 pounds or 3.78 kilograms at 62 °F

    Around 1 ohm is about 10 thou. I use thousanths of an inch at the wheel arch, and pounds at each corner, and then you do a linear reression to find out how different it is to pounds per square inches of your springs. If they are rising rate coils, or if the active coils differ, you just adjust the math a little. SN95's and long wheel base S-Foxes (the XR7, Thunderbird) have different lower control arm ratios, but the relationship is constant.

    smashed up SUV HID lamp Strain gauges are so cheap, and so darn accurate, so you then go out and do your work, and come back with the data trace, then your all good.

    For steering wheel angle and Yaw, I use the Texas DOT curve radius finder or a ball bank sensor or the cell phone app Accelerator-ometer, which can take the XYZ inputs from them, or an on board Nissan Stagea or Skyline Attessa 4WD gyro. Once you've got all that stuff in realtime, you can then pull out the traces.

  12. #12

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    I seem to remember reading that Jake Hidley at Maximum Motorsports say on a fox body no wing is particularly useful unless it was at least as tall as the roof. Guess the air down lower is so turbulent that it didn't help much.

    Jess
    Currently own;
    1979 Mustang, v6 swapped to EFI 393, custom installed m122 blower, 4r70w trans, Megasquirt II, T-top swaped in.
    Previously owned;
    1990 Mustang, 545 BBF, C-4 with brake, ladder bars.
    1983 Mustang, 1984 SVO Mustang
    1984 Mustang convertible, v6 swapped to 351
    1986 Mustang GT, 1989 Mustang GT convertible
    1992 Mustang coupe, 4 swapped to 302

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